linux-kernel - Re: [PATCH perf/urgent] perf tools: Fix is_bpf

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Message-ID: <20200512133609.GA3158213@krava>
Date:   Tue, 12 May 2020 15:36:09 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>
Subject: Re: [PATCH perf/urgent] perf tools: Fix is_bpf_image function logic

On Tue, May 12, 2020 at 10:32:23AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, May 12, 2020 at 02:23:10PM +0200, Jiri Olsa escreveu:
> > Adrian reported that is_bpf_image is not working the way it was
> > intended - passing on trampolines and dispatcher names. Instead
> > it returned true for all the bpf names.
> > 
> > The reason even this logic worked properly is that all bpf objects,
> > even trampolines and dispatcher, were assigned DSO_BINARY_TYPE__BPF_IMAGE
> > binary_type.
> > 
> > The later for bpf_prog objects, the binary_type was fixed in bpf load event
> > processing, which is executed after the ksymbol code.
> > 
> > Fixing the is_bpf_image logic, so it properly recognizes trampoline
> > and dispatcher objects.
> 
> This is not applying on top of torvalds/master, not tip/perf/urgent, and

right.. it's on top of your's perf/core.. I can rebase on perf/urgent

> you forgot to add the Fixes: line, lemme try to find this...

oops, sorry

Fixes: 3c29d4483e85 ("perf annotate: Add basic support for bpf_image")

jirka

> 
> - Arnaldo
>  
> > Reported-by: Adrian Hunter <adrian.hunter@...el.com>
> > Signed-off-by: Jiri Olsa <jolsa@...hat.com>
> > ---
> >  tools/perf/util/machine.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index 8ed2135893bb..d5384807372b 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -738,8 +738,8 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
> >  
> >  static int is_bpf_image(const char *name)
> >  {
> > -	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) ||
> > -	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1);
> > +	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) == 0 ||
> > +	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1) == 0;
> >  }
> >  
> >  static int machine__process_ksymbol_register(struct machine *machine,
> > -- 
> > 2.25.4
> > 
> 
> -- 
> 
> - Arnaldo
>